fix: marker labels show actual m-number from filename instead of time order

Extract the manual export counter (m1, m2, ...) from the output path
so timeline markers match their filenames. Falls back to sequential
numbering for old-format paths without m-prefix.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

core/db.py

@@ -1,4 +1,5 @@
 import os
+import re
 import sqlite3
 import threading
 from datetime import datetime, timezone
@@ -7,6 +8,12 @@ from pathlib import Path
 from .paths import _log
 
 
+def _extract_m_number(output_path: str) -> int | None:
+    """Extract the manual export number from a path like clip_001_m3_0.mp4."""
+    m = re.search(r'_m(\d+)[_.]', os.path.basename(output_path))
+    return int(m.group(1)) if m else None
+
+
 class ProcessedDB:
     _SCHEMA_VERSION = 4  # bump when schema changes
 
@@ -378,12 +385,13 @@ class ProcessedDB:
                 (match, profile),
             ).fetchall()
         seen_times: dict[float, tuple[float, int, str, float]] = {}
-        n = 0
+        seq = 0
         for t, p, dur, cnt, spr in rows:
             if t not in seen_times:
-                n += 1
+                seq += 1
+                num = _extract_m_number(p) or seq
                 span = (dur or 8.0) + ((cnt or 1) - 1) * (spr or 3.0)
-                seen_times[t] = (t, n, p, span)
+                seen_times[t] = (t, num, p, span)
         return list(seen_times.values())
 
     def get_markers(self, filename: str, profile: str = "default",
@@ -424,12 +432,13 @@ class ProcessedDB:
         result: dict[str, list[tuple[float, int, str, float]]] = {}
         for folder, folder_rows in by_folder.items():
             seen: dict[float, tuple[float, int, str, float]] = {}
-            n = 0
+            seq = 0
             for t, p, dur, cnt, spr in folder_rows:
                 if t not in seen:
-                    n += 1
+                    seq += 1
+                    num = _extract_m_number(p) or seq
                     span = (dur or 8.0) + ((cnt or 1) - 1) * (spr or 3.0)
-                    seen[t] = (t, n, p, span)
+                    seen[t] = (t, num, p, span)
             name = os.path.basename(folder)
             result[name] = list(seen.values())
         return result